Inclusion complexation of beta-chitin with linear aliphatic amines was studied by X-ray diffraction. All tested amines, C3 to C8 monoamines and C2 to C7 diamines with terminal amino groups, reversibly formed crystalline complexes with beta-chitin by immersion of dry chitin in pure liquid. Complex formation caused linear increase in the 010 sheet spacing of beta-chitin depending on the carbon number of amine. The complexes could be classified as type I and type II according to the increment of sheet spacing against carbon number. All monoarnines formed type II complexes. In dry conditions, diamine formed a type I complex though the type of diamine complex differed for guest species in wet conditions. Based on the unit cell dimension and thermogravimetry, type II and type I are likely to correspond to guest-host (amine-chitobiose) ratios of 2:1 and 1:1, respectively. These differences seem to arise from varied interactions between functional groups of chitin and amines.